HI,
I would use ?with() instead of ?attach.
sMean <- with(sorted,tapply(PRICE,ITEM,mean))
sMean
#Double Single Triple
# 352.4 379.9 563.5
parameter <- data.frame(Pname,Iname,stringsAsFactors=FALSE)
with(sorted,tapply(get(parameter[["Pname"]]),get(parameter[["Iname"]]),mean))
#Double Single Triple
# 352.4 379.9 563.5
A.K.
--------------------------------------------
On Tue, 3/4/14, Barry King <barry.k...@qlx.com> wrote:
Subject: [R] Using indirect arguments in tapply
To: "r-help@r-project.org" <r-help@r-project.org>
Date: Tuesday, March 4, 2014, 9:01 AM
I am reading parameters from an Excel
file but am having trouble using them
in tapply. Here is a mini-version of my problem.
------------------------------------------------------------------------------------------------------------------------------------------------
sorted <-
data.frame(c("Single","Single","Double","Double","Double",
"Triple"),
c(324.5, 435.3, 568.3, 345.4,
143.5, 563.5))
colnames(sorted) <- c("ITEM","PRICE")
attach(sorted)
sMean <- tapply(PRICE,ITEM,mean) # works but cannot
use column names
directly
# since reading them from an Excel file
into
# a parameter file
Pname <- c("PRICE")
Iname <- c("ITEM")
parameter <- data.frame(Pname,Iname) # This mimics
reading the specific
column names
# from Excel
# Now I want to indirectly reference the PRICE and ITEM
columns but this
does
# not work as expected
sMean2 <- tapply(parameter$Pname, parameter$Iname, mean)
--
Any assistance would be greatly appreciated.
__________________________
*Barry E. King, Ph.D.*
Chief Modeler
Qualex Consulting Services, Inc.
barry.k...@qlx.com
O: (317)940-5464
M: (317)507-0661
__________________________
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